Rightwing friends and communist foes say former prime minister was charismatic, formidable, warlike and uncompromising
United States
Barack Obama led tributes, describing Margaret Thatcher as "one of the great champions of freedom and liberty" and a true friend to the US. Former president George HW Bush and the Republican House speaker John Boehner also paid generous tributes.
Obama, in a statement from the White House, focused on her success in breaking gender barriers. "As a grocer's daughter who rose to become Britain's first female prime minister, she stands as an example to our daughters that there is no glass ceiling that can't be shattered," the president said.
"As prime minister, she helped restore the confidence and pride that has always been the hallmark of Britain at its best. And as an unapologetic supporter of our transatlantic alliance, she knew that with strength and resolve we could win the cold war and extend freedom's promise."
Thatcher was an icon for conservative figures in the US, both as partner of Ronald Reagan, the most popular Republican president since 1945, and as a champion of small government and balanced budgets. But her popularity extended well beyond the American right. With Reagan, she was widely viewed as being instrumental in the collapse of the Soviet Union.
There was praise too from Hollywood, with Meryl Streep, who played Thatcher in her declining years in The Iron Lady, expressing her admiration for Thatcher's pressing ahead with what she believed in, despite arousing a level of hatred normally confined to "mass murderers".
The former president Bill Clinton praised her achievement in becoming the first female British prime minister. He described her as a fearless leader. "Like so many others, I respected the conviction and self-determination she displayed throughout her remarkable life as she broke barriers, defied expectations and led her country," Clinton said.
"Here in America, many of us will never forget her standing shoulder to shoulder with President Reagan, reminding the world that we are not simply carried along by the currents of history – we can shape them with moral conviction, unyielding courage and iron will."
George Bush, who occupied the White House towards the end of Thatcher's premiership, said in a statement on behalf of himself and his wife Barbara: "Margaret was, to be sure, one of the 20th century's fiercest advocates of freedom and free markets – a leader of rare character who carried high the banner of her convictions, and whose principles in the end helped shape a better, freer world.
"The personal grief we Bushes feel is compounded by the knowledge that America has lost one of the staunchest allies we have ever known; and yet we have confidence that her sterling record of accomplishment will inspire future generations. May God bless the memory of Margaret Thatcher."
Henry Kissinger, secretary of state under presidents Nixon and Ford, told CNN: "She was a woman who [knew that] a leader needed to have strong convictions because the public had no way of orienting itself unless its leadership, its leaders, gave it the real push. She didn't think it was her job to find the middle ground."
Thatcher still has a resonance in the US today, being frequently cited in speeches by conservatives. CNN showed a passage of one of her speeches relevant to the present debate about curbing the debt.
Boehner, who is at the centre of the White House-Congress confrontation over debt and spending, described her as the greatest peacetime prime minister in British history. He said: "Margaret Thatcher, a grocer's daughter, stared down elites, union bosses and communists to win three consecutive elections."
Boehner added: "Americans will always keep Lady Thatcher in our hearts for her loyalty to Ronald Reagan and their friendship that we all admired. At this difficult hour, I send the condolences of the US House of Representatives to prime minister Cameron and the British people."
The Republican senator John McCain, who backed Reagan in his approach to the Soviet Union, described Thatcher as "one of the great leaders" of the last century.
"To have withstood the special hatred and ridicule, unprecedented in my opinion, levelled in our time at a public figure who was not a mass murderer; and to have managed to keep her convictions attached to fervent ideals and ideas – wrongheaded or misguided as we might see them now – without corruption – I see that as evidence of some kind of greatness, worthy for the argument of history to settle.
"To have given women and girls around the world reason to supplant fantasies of being princesses with a different dream – the real-life option of leading their nation – this was groundbreaking and admirable."
Russia
It was Krasnaya Zvezda, the Red Army's newspaper, that dubbed Thatcher the "Iron Lady" in a 1977 article. The title stuck around, but the Soviet Union didn't and the USSR's last premier, Mikhail Gorbachev, 82, said her death was "a sad thing" and described her as "a great politician" who "will remain in our memory and in history". He recalled how his relations with Thatcher "were difficult at times, not always smooth, but, serious and responsible from both sides".
"Personal relations formed gradually and became more and more friendly," he said. "Eventually, we managed to reach mutual understanding and it was a contribution to changing the atmosphere between our country and the west and to stopping the cold war."
The Russian president, Vladimir Putin, said: "We have lost a strong political figure." He issued his condolences "in the name of the Russian leadership". He said Thatcher always brought "very strong impressions" and that she was "pragmatic, strict and responsible".
Even Russia's hardliners found something to respect.
"She is the greatest woman, the greatest politician," said Leonid Kalashnikov, a Communist deputy. "As an opponent, I always respected her. And how she, with the Americans, 'strangled' the Soviet Union is also worth quite a lot – because she did it correctly, logically and in their own interests."
Former deputy PM Boris Nemtsov recalled her visiting the city of Nizhny in 1994 as Russia opened up to the world. "We went into [a] shop and Thatcher bought cheese and came out to see hundreds of city residents waiting for her," he said. "People were so amazed that they started to shout 'Thatcher for president of Russia!' The baroness asked me, what are they screaming? She laughed and said, when Gorbachev moves to London they yell that it's time he became PM of the UK. They were similar. Neither one nor the other was loved in their motherland, but were respected abroad."
The influential political analyst Stanislav Belkovsky reflected on how Thatcher had been unswerving in her criticism of the "evil empire".
"Until her coming to power, the western establishment thought that the USSR and communism were permanent, so you don't have to struggle against them, but come to terms with them," he told the Izvestiya newspaper . "It was Thatcher and then Reagan who brought the totally new idea that communism can be beaten and destroyed. And they did it."
South Africa
Reaction to Thatcher's death was divided around her stance on the ruling African National Congress, which she once described as "a typical terrorist organisation", and her support for the former apartheid government.
"I don't think she ever got it that every day she opposed sanctions, more people were dying, and that the best thing for the assets she wanted to protect was democracy," said Dali Tambo, son of the former ANC president Oliver Tambo. "Many lives were lost. It's a shame that we could never call her one of the champions of the liberation struggle. Normally we say that when one of us goes, the ANC ancestors will meet them at the pearly gates and give them a standing ovation. I think it's quite likely that when Margaret Thatcher reaches the pearly gates, the ANC will boycott the occasion."
"I say good riddance," said Pallo Jordan, the ANC's chief propagandist in exile during the apartheid era. "She was a staunch supporter of the apartheid regime. She was part of the rightwing alliance with Ronald Reagan. In the end I sat with her in her office with Nelson Mandela in 1991. We knew she had no choice. Although she called us a terrorist organisation, she had to shake hands with a terrorist and sit down with a terrorist. So who won?"
But the country's last apartheid-era president, FW de Klerk, saluted her as "one of Britain's greatest prime ministers" and said she played a positive role in the process of non-racial constitutional transformation.
"Although she was always a steadfast critic of apartheid, she had a much better grasp of the complexities and geostrategic realities of South Africa than many of her contemporaries," he said. "She consistently, and correctly, believed that much more could be achieved through constructive engagement with the South African government than through draconian sanctions and isolation.
The ANC government of the current president, Jacob Zuma, said: "The ANC was on the receiving end of her policy in terms of refusing to recognise the ANC as the representatives of South Africans and her failure to isolate apartheid after it had been described as a crime against humanity," a statement from the ruling party said.
"However, we acknowledge that she was one of the strong leaders in Britain and Europe to an extent that some of her policies dominate discourse in the public service structures of the world. Long after her passing on, her impact will still be felt and her views a subject of discussion."
Germany
Chancellor Angela Merkel, who has been dubbed the Iron Lady of Europe for her tough line over the eurozone crisis, called Thatcher a "formidable leader in world politics in her time".
"The freedom of the individual stood at the core of her beliefs, therefore, Margaret Thatcher recognised the power of the freedom movement in east Europe early on and supported it," she said. "I will not forget her part in overcoming the European division and in the end of the cold war. Margaret Thatcher was not a politician for women, but that she led the highest democratic office as a woman, in times where that was not a given, she set an example for many after her."
Michael Roth, of the opposition Social Democratic party, said "her edge and her charisma" would be missed.
"Such special politicians, with special stories shaped by the second world war and the subsequent years of rebuilding, have become rarer in the younger generation," he said.
But he added: "Her radical market policies and her Europe-sceptical politics will certainly not be missed. Her politics seem to not have gone out of fashion, as evidenced by the radical savings and austerity policies in crisis countries, such as Greece, Portugal and Spain. That Thatcher legacy is obviously very present there. She had the sort of politics that I, as a social democrat, obviously find to be wrong, but that are still in effect today."
The German foreign minister, Guido Westerwelle, said she "leaves behind a big legacy for European history. We look upon her life's work with wonderment."
France
Jean-François Copé, leader of the centre-right French opposition, was among right-leaning European politicians who hinted that Thatcher's legacy held lessons for the reform of struggling EU economies. "She set her goal and stayed the course in the face of all the arguments and succeeding in bringing a spectacular modernisation to the British economy," he said.
France's socialist president, François Hollande, said she was "a great personality who profoundly marked the history of her country".
"Throughout her public life, with the conservative beliefs that she fully assumed, she nurtured the influence of the United Kingdom and the defence of its interests," he said.
"The relations she maintained with France were always frank and loyal. She knew how to build a constructive and fruitful dialogue with François Mitterrand. Together, they set about reinforcing the ties between our two countries. It was in that era that Mme Thatcher gave the decisive push to the construction of the Channel tunnel."
Le Monde, which reminded readers of the late President Mitterand's remark that "she has the mouth of Marilyn [Monroe] and the look of Caligula", said: "She demonstrated the character traits that founded her reputation: an inflexible will, bordering on intransigence; an almost faultless self control; above all, the certainty of being right against all winds and tides."
Spain
Spanish prime minister Mariano Rajoy hailed Thatcher as "a true landmark in 20th-century history" and said it was "a sad day for Europe as a whole".
"Margaret Thatcher led the UK government at a key moment in history. Her unerring commitment to freedom, democracy and the rule of law, as well as her firm determination to reform, constitute a most valuable legacy for European leaders who, akin to the 80s when it was her turn to be in power, have to face very complex challenges which require greatly ambitious stances and political courage."
Eastern Europe
Thatcher was hailed as a champion of freedom and the free market across central and eastern Europe, where she and Ronald Reagan were seen as the west's pre-eminent cold war warriors.
In Poland, where on a 1988 visit she met Lech Walesa, then leader of the pro-democracy Solidarity union to support the fight against communism, Walesa remembered Thatcher as "a great person".
"She did a great deal for the world, along with Ronald Reagan, Pope John Paul II and Solidarity, she contributed to the demise of communism in Poland and central Europe," he said.
Monuments to Reagan and John Paul II already stand in Poland, and now Thatcher deserved hers, Poland's foreign minister, Radoslaw Sikorski, said, calling her a "fearless champion of liberty [who] stood up for captive nations."
In Prague, Vaclav Klaus, a staunch Eurosceptic who has just left office after a decade as Czech president, called her death "a huge loss for all supporters of freedom, democracy and market capitalism".
"She was one of the most outstanding political personalities of the last quarter of the 20th century and I believe that with the passing of time, her name will not lose importance," he said.
India
Manmohan Singh, India's prime minister, expressed his "deepest sadness He said: "She was a transformative figure under whom the United Kingdom registered important progress on the national and international arena."
Narendra Modi, the chief minister of Gujarat state, popular among the country's businessmen but accused of rightwing Hindu nationalist views by many, saluted an "inspirational leader of immense stature and fortitude, Baroness Margaret Thatcher was an epoch maker".
Reports focused on Thatcher's friendship with Indira Gandhi, the prime minister of India who was assassinated by her bodyguards in 1984 after ruling for all but three years since 1966.
"Very early on, [Indira Gandhi and I] struck up a close rapport, for we both felt the loneliness of high office and it was good to be able to talk to someone who understood … Gandhi's death by terrorism is forever linked in my mind with my own survival of it," Thatcher later said, IANS, an Indian news service, reported.
Thatcher said that she and Gandhi, who launched a massive nationalisation campaign which fundamentally changed India's economy and suspended democracy to impose a two-year emergency "had very different ideas about politics."
"But I found in her qualities which seem to me essential in a statesman. She was passionately proud of her own country, always courageous and very practical."
Afghanistan's president Hamid Karzai, a former mujahadeen who fought the Soviets with Thatcher's support in the 1980s, offered condolences and said she would be missed as "a great stateswoman".
"Prime minister Thatcher was one of the greatest leaders the world knew," he said. She would always be remembered in history as "a well-known and strong leader who had truly served her country, particularly in strengthening UK's economy".
Chile
In Santiago, former supporters of Chilean the dictator, General Augusto Pinochet, talked of Thatcher's "bravery" in supporting his regime at a time when his military government was being accused of killing, interning and tortured his enemies.
Pinochet died in 1990, but those close to him said Thatcher was a great statesperson. "Personally, I see her as a world leader, who was consistent and absolute in her defence of her nation," said General Guillermo Garin, retired vice-commander in chief of the Chilean army.
"Regarding Chile, during the military government, she was very brave. She recognised the origins of the [1973 military coup] and the benefits of the military government … She was a defender of the grand modernisations that Chile put in place and expressed her support versus a very hostile campaign run by the Soviet Union. President Pinochet always had tremendous admiration for her, they had a very close relationship highlighted by the visit she made to his place of detention in London … They shared similar concepts of modernisation of the state."
Ghana
"Thatcher was warlike and uncompromising in her ways," said Ghana's former president John Agyekum Kufuor.
"I know that in her country some people admired her for that, but to many of us that wasn't impressive. We in Ghana were very critical of the way she led her country into war in South America – she seemed too ready to resort to force to settle the Falklands. And her position on the ANC wasn't acceptable. She proved to be too conservative; she didn't seem to appreciate the rapidly changing world."
But he saluted her economics. "She believed that there are only a few creators in this world, entrepreneurs and investors, and that you protect them – they are the people who will increase the wealth of the nation and create jobs for people. That is a philosophy I also subscribe to."
Nigeria's former military leader Ibrahim Babangida said he had agreed with Thatcher's policy on "constructive engagement" with South Africa, and that had informed Nigeria's own stance.
"[Thatcher] told us that its about time that we engaged South Africa in constructive engagement, and that is perhaps the best way to get rid of apartheid. I took her advice and invited De Klerk to this country. I think she was a fine example of a very courageous political leader. She is admired greatly by a majority of countries in Africa," he said
Israel
Prime minister Binyamin Netanyahu said he was in mourning and sent condolences to the people of Britain, describing Thatcher as "a truly a great leader, a woman of principle, of determination, of conviction, of strength; a woman of greatness".
"She was a staunch friend of Israel and the Jewish people. She inspired a generation of political leaders."
Shimon Peres, the current president of Israel who was prime minister and foreign minister during Thatcher's premiership, said: "There are people, there are ideas. Occasionally those two come together to create vision. Lady Thatcher was an exceptional leader, a colleague in the international arena and a friend for me personally. She served as an inspiration for other leaders, as the first female prime minister of Great Britain she broke new ground. She showed how far a person can go with strength of character, determination and a clear vision."
Peres praised Thatcher for standing by Israel in times of crisis. "During our negotiations with Jordan in the late 1980s, she stood as a mediator and a source of wisdom for me and the king of Jordan," he said.
Japan
The prime minister, Shinzo Abe, had recently invoked Thatcher's resolve during the Falklands war in his country's ongoing territorial dispute with China. Abe called her a "great statesperson" and Japan's deputy chief cabinet secretary, Hiroshige Seko, said Abe had "great respect" for Thatcher and identified with her conservative agenda for economic reform.
China
Hu Xijin, editor in chief of the populist state-run tabloid Global Times, wrote: "People's most striking memory is of her 'being tough'. As a successful woman in politics, she was revered. As a politician, her experience and policies stirred feelings."
But he added: "The 'Iron Lady' era is over. Today is the era of co-operation."
The state broadcaster CCTV talked of the death of the tie niang zi – Iron Lady – noting her meetings with the then leader Deng Xiaoping to discuss the handover of Hong Kong, but devoting as much time to her childhood, rise through the ranks and political career. It noted her free market policies, concerns about the wealth gap and unemployment rate under her governments, and the Falklands war.
Shi Yinhong, an expert on foreign relations at Renmin University, said: "I think Chinese people respected her and positively assessed her historical role.
"Although in the process of Hong Kong's return to China and the negotiations there were some difficulties between Mrs Thatcher and our great leader Deng Xiaoping, Britain and China successfully overcame them and both sides made efforts to smooth the transfer of sovereignty.
"My guess is that they had something in common in their strategic and political responsibilities. Both were very determined, responsible people who were not afraid to speak frankly to the other side. They could respect and understand each other's national interests."